In connection with so-called jump-lifts, an elevator is taken into use already before the full length of the elevator hoistway has been completed. The elevator car moving in the bottom part of the elevator hoistway is supported and moved during the construction-time use suspended on hoisting ropes that are supported by a supporting structure in the elevator hoistway, which ropes are moved with a hoisting machine. The top part of the elevator hoistway above the supporting structure is constructed at the same time as an elevator car moving in the already completed bottom part of the elevator hoistway serves people on the lower floors of the building. The hoisting machine can be supported e.g. on the supporting structure. When the part of the elevator hoistway under construction above the supporting platform has reached a sufficient stage of readiness, it can be taken into use. In this case a lift (a so-called jump-lift) is performed, wherein the supporting platform is raised to a higher position in the elevator hoistway, thus extending the service range of the elevator car upwards. A worksite crane in use in the construction of the building can, for example, be used for the lifting. Alternatively, the supporting structure could be shifted with a hoist, which is supported on a support structure to be arranged in the hoistway above the machine room platform. When the elevator hoistway has reached its final height, the elevator is left permanently in its position, possibly however first performing some conversion procedures, e.g. by removing the elements required for jump-lifts, possibly by replacing the roping and/or by changing its route. One solution according to prior art is described in publication WO 2010100319.
One problem in solutions according to prior art has been the large weight of the structures to be hoisted in lifting the supporting structure. More particularly the roping hanging from the supporting structure is supported during a lift by the hoist moving the supporting structure. The hoist itself and the hoisting arrangement generally must be dimensioned to be heavy-duty. Likewise the support points for the structures, more particularly for the hoisting arrangement of the supporting structure, but also for supporting the supporting structure in its position, have been difficult to arrange. It has been noticed that the difficulty of finding support points that are sufficiently stable and durable is one limiting the maximum height to which a jump-lift can, with a reasonable work input, reach. A worksite crane must sometimes be used for shifting the machine room platform, because the aforementioned problems make other solutions so awkward. Another problem has been, generally speaking, the demanding installation environment, which has set numerous practical challenges, which are connected to the smooth running and safety of the installation and to the durability of installation structures. These are, inter alia, the space usage and complexity of the hoisting arrangement for the machine room platform, the center of mass and stability of the machine room platform during the lifting and while it is stationary in position, the center of mass and stability of the support arrangement to be used for the lifting during the lifting and while in position, the layout producing a suitable balance of the support locking mechanism, the cramped layout of the machine room platform, suitable hoisting devices, the dimensioning of the hoisting machine for the final lifting height, routing of the ropes with adequate run clearances, correct configuration of the rope length, the need for safe and spacious working space and position. These numerous variables that must be taken into account affect each other directly or indirectly and their overall effect is that the structure easily becomes complex and heavily built, and requires a lot of space. Taking these challenges into account, there has been a need to further simplify the supporting structure to be lifted in a jump lift and to reduce the weight to be lifted in a jump lift. Likewise, there has been a need to further develop the safety and speed of the method.